1. Field of the Invention
The present invention relates to connectors configured to connect to multi-conductor ribbon cable and, in particular, concerns a connector that is configured to connect to both signal conductors and ground conductors defining a ground bus in the multi-conductor cable.
2. Description of the Related Art
Ribbon cable is a type of cable which has a plurality of conductors positioned adjacent each other in a single plane. Typically, the conductors are encased in a flexible insulating material, such as vinyl, which follows the contours of the parallel closely spaced conductors in the ribbon cable. Ribbon cable is often used to interconnect computer components. One common example of the use of ribbon cable is to connect motherboards in personal computers to disk drives. Further, ribbon cable is also often used to interconnect computers to accessory equipment.
Generally, connectors are used to interconnect the cables to various devices. These connectors have a plurality of contacts which are configured to contact the conductors within the ribbon cable and also to provide a pin connection to a matching connector or pin array. Typically, the connectors include a plurality of contacts that have an insulation displacement end that pierces the insulation surrounding the conductor in the ribbon cable and contacts the embedded conductor, and a mating end that provides a connection point for pins of a mating connector or pin array.
The typical connector is generally rectangular in shape and has an opening which receives the ribbon cable so that the connector spans the width of the ribbon cable. The insulation displacement ends of the plurality of contacts are positioned within the connector so that when the connector is closed around the ribbon cable, the insulation displacement ends pierce the insulation surrounding the conductors of the ribbon cable and form an electrical connection with each of the conductors within the ribbon cable. It will be appreciated that the contacts are exactly positioned within the connector so as to be able to contact and make an electrical connection with the corresponding conductor within the ribbon cable.
One typical ribbon cable assembly application used in the prior art has forty conductors that are spaced on 0.050" centers. Of the forty conductors within the cable, seven of these conductors are dedicated as ground conductors and the remaining thirty-three are data line or signal conductors. This type of ribbon cable complies with ANSIx3.279-1996 specification. The structure of the prior art ribbon cables results in these ribbon cables having an upward limit of approximately 16 MB/Sec. data transfer rate over the ribbon cable.
As computers have become increasingly more powerful, there has been a desire to increase the rate of data transmission over ribbon cables. This has resulted in the creation of a new ribbon cable specification, the SFF-8049 specification. Ribbon cables corresponding to the SFF-8049 specification will now have eighty conductors that are spaced apart on 0.025" centers. Hence, the ribbon cable under the new specification will have the same general size, otherwise known as form factor, as the ribbon cable of the prior art. The ribbon cable of the new specification retains the forty original signal conductors, the 33 data conductors and the 7 ground conductors, of the prior art ribbon cable. This permits use of the new specification cable in the place of the old specification ribbon cable without requiring the alteration of the input and output devices that are connected to the ribbon cable.
However, the forty additional conductors that are added to the ribbon cable of the new specification are all ground conductors that are positioned between each of the original forty conductors. Consequently, the original signal conductors are separated from each other by a dedicated ground conductor in the new specification cable. Hence, the forty additional ground conductors form a ground bus which results in the new specification ribbon cable being able to transmit data at a significantly higher rate than the old specification ribbon cable.
However, the introduction of the new specification ribbon cable has complicated the task of connecting devices to the new specification ribbon cable. In particular, the forty conductors forming the ground bus must be grounded to each termination of the ribbon cable and at any mid-length connection to the ribbon cable for the ground bus to function most effectively. Presently, to achieve this connection, a first prior art connector that was originally configured to attach to the forty original conductors is slightly modified so that the contacts will selectively engage with the forty original signal conductors in the new specification cable when mounted on the ribbon cable. A second connector, similar in construction to the first connector, that is configured to attach to the forty alternating ground conductors that comprise the ground bus is then mounted on the ribbon cable.
While the use of the two connectors results in adequate connection to the forty original signal conductors and the forty added ground conductors, using two connectors is more costly and also increases the possibility of poor connection to the conductors within the ribbon cable. Further, the use of two connectors at each termination or mid-length connection to the ribbon cable complicates the use of the ribbon cable particularly in environments where the space surrounding the ribbon cable is limited.
Moreover, it is desirable to attach the seven original grounded signal conductors to the ground bus at each connector. Presently, this is accomplished by stringing jumpers between the pin connections of the seven ground conductors on the first connector to the ground contacts on the second connector. However, this sort of interconnection complicates the installation of the connectors to the new specification ribbon cable as this must typically be done by hand after the cable has been installed.
Hence, there is a need for a connector that can be connected to the new specification ribbon cable which will connect to both the forty original signal conductors and also to the forty ground bus conductors. This connector should preferably have a form factor that is substantially the same as the form factor of the connectors used in the prior art. Further, this connector should also be configured so that interconnection between the forty ground conductors and the seven original signal ground conductors is simplified.